Ok, I did a clean install of 10 Home from the latest 1709 (fall update) x86x64 MCT thumb drive. Just did the change key and entered the 3V66T key. It was accepted and it did the upgrade to Pro. It just rebooted as I'm typing this. It's showing Windows 10 Pro, activated with a Digital License linked to your Microsoft account.

My ComputerYou need to have JavaScript enabled so that you can use this ...

It's dejá vu all over again. :doh:
The correct behaviour of windows update over a metered connection is to offer the choice to download, or wait until on a non-metered connection.
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The initial build of the Anniversary Update broke...

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